If you’re not already doing this, creating an invalidation for CloudFront will dramatically speed up the propagation. See the docs here: http://docs.aws.amazon.com/cli/latest/reference/cloudfront/create-invalidation.html.

A quick script example:

“deploy”: “npm run test:once && npm run build && aws s3 sync build/ s3://<bucket> --cache-control max-age=172800 --delete && aws configure set preview.cloudfront true && aws cloudfront create-invalidation --distribution-id <dist-id> --paths /index.html”